1. Field of the Invention
This invention concerns a sleeping bag constructed of side by side chambers formed by dividing walls and filled with stuffing material, inner and outer shells that cover the chambers and a zipper.
2. Description of the Related Art
Sleeping bags designed for various purposes have been available in many different styles for a long time. When sleeping outdoors (without a tent), it is desirable to have protection from dampness and wetness caused by rain, dew, or snow. For this reason, sleeping bags are available with waterproof outer shells.
One example in current use is Super Dryloft from Gore, a membrane made of stretched Gore-Tex that is laminated onto nylon. Stretching the membrane increases the membrane's water vapor-permeability. However, it is moisture resistant and completely windproof. Micro-fiber fabrics, such as Pertex nylon, are used for less demanding requirements. Although these sleeping bags are essentially waterproof, they exhibit weak spots, especially in places where there are external seams.
In order to address this issue, it has been proposed to equip sleeping bags with separate outer coverings (like that available under the trade name C-tex) under which is located a cover made of vapor-permeable laminate. However, this necessitates carrying and packing an additional item.